Why do you want to remove the locks? I would never do it. Some bored kid or someone upset with you for real or imagined reasons could easily destroy your engine by pouring things in there "just for fun".

Our 2001 and 2013 Adventurers came with the non-locking door as posted by Tomtall. In both cases I went to the local hardware store and purchased a similar sized keyed mail box lock. It took about 10 minutes to change it out.